Hitachi pump stop/start when running .

[Andrew Dwyer]

So, my Hitachi WM-P150XX pump is stopping (briefly, a second or two ) when running and appears to be getting more frequent.

 

Up until a few days ago it would run continuously when the toilet was flushed until toilet was full.

I first noticed it stopped once when filling, now it is stop/start 4 times.

Same for all other water outlets, bathroom sink, kitchen sink etc .

Water flow or pressure doesn’t appear to have changed though just an annoying stop/start frequency.

It now runs like someone has opened a tap just a little bit but the flow/pressure says otherwise.

 

Pump is around 3 or 4 years old.

 

Any ideas ?

[Crossy]

Water logged pressure tank.

 

You should be able to find the drain procedure online.

[Andrew Dwyer]

It’s a pump with the screw on bladder tank. I bought a replacement tank around 8 months ago for another issue ( loud knocking sound when pump shut off, this didn’t cure the problem but it disappeared a few days later, someone suspected the non return valve was open with a leaf of the suchlike ).

 

Tried replacing the original tank which gives me exactly the same stop/start issue ( now have 2 tanks that am not sure if good or not ! ).

 

Doesn’t appear any way to charge the tank, has a security torx screw in the top, have no idea how they charge these.

 

 

 

Will probably seek a local repair shop to see if they can check pressure in tank to eliminate.

 

What ya think ?

[Crossy]

Ah. Those are not rechargeable, you could try taking it off and shaking the water out. If it has failed you can get pattern replacements that have a tyre valve to pump up.

 

Leaky non return valves make it cycle when not using water.

[Crossy]

Also in the frame could be the pressure switch. 

[Andrew Dwyer]

27 minutes ago, Crossy said:

Ah. Those are not rechargeable, you could try taking it off and shaking the water out. If it has failed you can get pattern replacements that have a tyre valve to pump up.

 

Leaky non return valves make it cycle when not using water.

Shame it doesn’t have a valve on there, only 11.6 psi, could bang some air in there in no time and check the pressure if suspecting has leaked out .

[ravip]

6 hours ago, Andrew Dwyer said:

It’s a pump with the screw on bladder tank. I bought a replacement tank around 8 months ago for another issue ( loud knocking sound when pump shut off, this didn’t cure the problem but it disappeared a few days later, someone suspected the non return valve was open with a leaf of the suchlike ).

 

Tried replacing the original tank which gives me exactly the same stop/start issue ( now have 2 tanks that am not sure if good or not ! ).

 

Doesn’t appear any way to charge the tank, has a security torx screw in the top, have no idea how they charge these.

 

 

 

Will probably seek a local repair shop to see if they can check pressure in tank to eliminate.

 

What ya think ?

 

[ravip]

Our Hitachi GX Series WMP200GX2 was switching on/off for a fraction of a second every now and then when not in use. One tech replaced the non return valve, but didn't solve the issue. 

Finally found a small leak on the grey part with the yellow stopper (forgot the name) and replaced it. 

All fine now. Bought from Shoppee THB 265. Hitachi Thailand was very helpful and answered all my emails. 

 

Just for your information. 

 

Add

Just 2 weeks ago

[Raindancer]

38 minutes ago, ravip said:

Our Hitachi GX Series WMP200GX2 was switching on/off for a fraction of a second every now and then when not in use. One tech replaced the non return valve, but didn't solve the issue. 

Finally found a small leak on the grey part with the yellow stopper (forgot the name) and replaced it. 

All fine now. Bought from Shoppee THB 265. Hitachi Thailand was very helpful and answered all my emails. 

 

Just for your information. 

 

Add

Just 2 weeks ago

Thanks for the info.

 

[Fruit Trader]

This model pump (Hitachi WM-P150XX) has a combined flow/pressure switch device which attempts to deliver constant pressure and reduce cycling. If this device becomes defective or clogged pump operation can become erratic.

 

Top of module can be removed to clean and inspect components inside.
 

 

 

 

 

 

module can be removed to clean and inspect components inside.

 

 

[Andrew Dwyer]

10 hours ago, Fruit Trader said:

This model pump (Hitachi WM-P150XX) has a combined flow/pressure switch device which attempts to deliver constant pressure and reduce cycling. If this device becomes defective or clogged pump operation can become erratic.

 

Top of module can be removed to clean and inspect components inside.
 

 

 

 

 

 

module can be removed to clean and inspect components inside.

 

 

 

Thanks for this, it is called a “ life save unit “ apparently and consists of a diaphragm and a spring sitting underneath the pressure switch:

 

it was a little dirty with hardened lime scale on the diaphragm which could possibly effect the flexibility and give some varying pressures to switch above ? ( am guessing here ).

 

 

gave it a good old clean and opened the incoming valve just to check clean water was flowing.

Put it back together and initially it looks to have done the trick !!

Toilet fills without the pump stop/start now but a lot of air in pipework now so will let that clear over a couple of days before celebrating.

 

Thanks @Fruit Trader

 

Had a little look at pressure switch to see if anything untoward there but looks like new and a different type to what i have seen previously.

 

Just for info.

 

[SAFETY FIRST]

I'd say that you have air in your holding tank. 

Air takes up space, it will reduce the amount of water held in the reservoir, reducing capacity. 

 

My tank has an unscrew valve, I loosen while pump is running, let's the air escape. 

 

 

[Andrew Dwyer]

1 hour ago, SAFETY FIRST said:

I'd say that you have air in your holding tank. 

Air takes up space, it will reduce the amount of water held in the reservoir, reducing capacity. 

 

My tank has an unscrew valve, I loosen while pump is running, let's the air escape. 

 

 

Yes, always keep the hopper full by unscrewing the yellow cap a little until air has escaped.

 

[Andrew Dwyer]

Well, it appears it was as Fruit Trader said, the aforementioned “ Life Save Unit “ which I had seen on the manual drawing and had no idea what it was .

On taking it apart was expecting to see some sort of last chance mesh filter !

 

Expect the build up of lime scale affected the flexibility of the diaphragm in turn affecting the pressure reading by the switch ??

Saved me time and money as was thinking could only be the bladder tank or the pressure switch at fault.

 

You live and learn ……… well I did !